const { merge } = require('webpack-merge');
const commonConfig = require('./webpack.common');
const { DefinePlugin } = require('webpack');

const HtmlWebpackPlugin = require('html-webpack-plugin');

const { CleanWebpackPlugin } = require('clean-webpack-plugin');

const MiniCssExtractPlugin = require('mini-css-extract-plugin');

const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin');

const TerserPlugin = require('terser-webpack-plugin');

const path = require('path');

//生产环境的配置
module.exports = merge(commonConfig, {
  mode: 'production',
  //去除sourceMap
  devtool: 'none',

  //输出的文件名
  output: {
    filename: 'js/[name].[hash:8].js',
    publicPath: './',
  },
  //更改css和less的loader
  module: {
    rules: [
      {
        test: /\.less$/,
        use: [MiniCssExtractPlugin.loader, 'css-loader', 'less-loader'],
      },
      {
        test: /\.css$/,
        use: [MiniCssExtractPlugin.loader, 'css-loader'],
      },
    ],
  },

  plugins: [
    new HtmlWebpackPlugin({
      template: './public/index.html',
      favicon: './public/favicon.ico', // 在此处设置
      //对html代码进行压缩
      minify: {
        removeComments: true, //去注释
        collapseWhitespace: true, //压缩空格
        removeAttributeQuotes: true, //去除属性引用
      },
    }),
    new DefinePlugin({
      BASE_URL: process.env.NODE_ENV,
    }),
    //用于每次生成的时候，清理上次的打包文件
    new CleanWebpackPlugin(),
    new MiniCssExtractPlugin({
      filename: 'css/[name].[hash:7].css',
      chunkname: path.posix.join('static', 'css/[id].[chunkhash:7].css'),
    }),
  ],
  optimization: {
    //代码分包
    splitChunks: {
      chunks: 'all',
    },
    minimize: true,
    minimizer: [
      //css压缩
      new OptimizeCSSAssetsPlugin({
        cssProcessorOptions: {
          discardComments: { remove: true }, //移除注释
        },
      }),
      new TerserPlugin({
        parallel: true, //开启多线程来提高构建速度
        sourceMap: false,
        terserOptions: {
          warnings: false, //不展示warning
          compress: {
            unused: true, //去除未使用的
            drop_debugger: true, //移除debugger
            drop_console: true, //去除console
          },
          output: {
            comments: false, //去除注释
          },
        },
      }),
    ],
  },
});
